Electrical cable having integral terminals

ABSTRACT

Electrical cable comprises an elongated strip of sheet metal which is axially slit intermediate its ends to define a plurality of strands. The slit strands of the cable are integral with a transition section at each end of the cable which in turn is integral with a terminal. The cable is preferably manufactured by forming the sides of the transition section inwardly and towards each other and then twisting the entire cable to impart a helical configuration to the strands. Insulation may be provided by dipping the intermediate portion of the cable into a plastisol which hardens on the surface of the strands, which penetrates between the strands, and which seals the ends of the cable.

United States Patent Bunnell [541 ELECTRICAL CABLE HAVING INTEGRAL TERMINALS [72] Inventor: Edward Dennman Bunnell, Palm Harbor, Fla.

[73] Assignee: AMP Incorporated, Harrisburg, Pa.

[22] Filed: April 28, 1971 [21] Appl. No.: 138,162

[52] 0.8. Cl ..-339/28, 29/624 R, 57/ 154, 57/155, 57/165, 57/167, 174/126 R, 339/224 [51] Int. Cl. ..1-l01r 11/00 [58] Field of Search....339/28, 29, 224, 277, 275 RB, 339/276 RB; 174/69, 126; 238/1405; 29/624 R [56] References Cited UNITED STATES PATENTS 2,927,953 3/1960 Staller..... ....174/69 3,181,110 4/1965 Waters. ..339/223 2,479,834 8/1949 Herbert ..339/224'X 1,789,951 1/1931 Terrell et al. ..3 39/28 X 2,939,905 6/1960 Canfield ..174/69 X 2,654,873 10/1953 Swengel ..339/277 R 1,581,133 4/1926 Mackenzie ..l74/69 X FOREIGN PATENTS OR APPLICATIONS 473 .798 10/1937 Great Britain ..339/29 R Primary Examiner-Joseph H. McGlynn Assistant Examiner-Terrell P. Lewis Attorney-William J Keating, Ronald D. Grefe, Gerald K. Kita, Frederick W. Raring, Jay L. Seitchik, John R. Flanagan and Allan B. Osborne [57 ABSTRACT Electrical cable comprises an elongated strip of sheet metal which is axially slit intermediate its ends to define a plurality of strands. The slit strands of the cable are integral with a transition section at each end of the cable which in turn is integral with a terminal. The cable is preferably manufactured by forming the sides of the transition section inwardly and towards each other and then twisting the entire cable to impart a helical configuration to the strands. Insulation may be provided by dipping the intermediate portion of the cable into a plastisol which hardens on the surface of the strands, which penetrates between the strands, and which seals the ends of the cable. I

9 Claims, 10 Drawing Figures PATENTED DEC 19 912 SHEET 2 OF 2 ELECTRICAL CABLE HAVING INTEGRAL TERMINALS BACKGROUND OF THE INVENTION This invention relates to electrical cables formed from sheet metal having integral terminal means on their ends. The invention is herein disclosed in an embodiment comprising a cable intended for use with a conventional automotive battery but other uses for cables in accordance with the invention will be apparent to those skilled in the art.

The following U.S. Pat. Nos. illustrate the state of the art of the instant invention: Godwin et al. 3,337,834; Webb 3,422,213; Binder 1,854,328; Gribble 1,697,954; Julyan 1,690,118.

Large diameter electrical cables intended for high amperage service, such as the cables used for the connections to the terminals of a conventional automotive battery, require relatively massive terminals as compared with the terminals required for smaller wires such as house wires or the wires required for lighting and ignition circuits of an automobile. These larger terminals are usually forged or cast and are relatively expensive. In fact, it is quite often true that the terminals on the ends of a automotive battery cable represent the major portion of the cost of the finished cable.

-It has been suggested that under many circumstances, wiring costs can be reduced by using aluminum cables and conductors rather than conventional copper wires. In the case of an automotive battery cable, some saving in the cost of the conductors can be realized if aluminum cable is used rather than copper cable but the cost of terminals for aluminum cable are greater, other things being equal, than the cost of terminals for copper cable because of the corosion problem. Furthermore, the corosion problem normally associated with aluminum cables is aggravated by the environment in which a battery cable must be used. For this reason, and for other reasons, aluminum battery cables have not been widely used in the past.

The instant invention is directed to an improved cable having integral terminals on its ends and particularly to an improved cable intended for use with a conventional automotive battery. It is accordingly an object of the invention to provide an improved electrical cable formed from strip metal'having integral terminals on its ends. A further object is to provide a cable which can readily be insulated and sealed against penetration by corosive fluids. A still further object is to provide an improved method of manufacturing an aluminum cable having an aluminum terminal on its ends. A further object is to provide a practical and efficient manufacturing method for electrical cables.

These and other objects of the invention are achieved in a preferred embodiment thereof which is briefly described in the foregoing abstract, which is described in detail below, and which is shown in the accompanying drawings in which:

FIGS. 1-4 are a series of perspective views illustrating the manufacture of electrical cables in accordance with one embodiment of the invention from an elongated strip of sheet metal such as aluminum or copper.

FIGS. 5 and 6 are views taken along the lines 5-5 and 6-6 of FIG. 4.

FIG. 7 is a view taken along the lines 7--7 of FIG. 2.

FIG. 8 is a cross sectional view of a modified form of round cable in accordance with the invention.

FIG. 9 is a fragmentary view of a flat cable in accordance with the invention.

FIG. 10 is a perspective view of a cable having a terminal on one end thereof which is adapted to be connected to a conical battery terminal.

The structure of an electrical cable in accordance with the invention can best be understood from a description of one preferred method of manufacturing a cable in accordance with the invention. Referring to FIG. 1, a cable suitable for use with a conventional automotive battery can be manufactured from a strip 2 of relatively pure aluminum having a thickness of about 0.040 inches. A preferred grade of aluminum for the manufacture of the cable is alloy 1100-0, a commercially pure aluminum in a dead soft condition. The length of the strip 2 should, of course, be equal to the required length of the finished cable.

As shown in FIG. 2, the strip 2 is axially slit intermediate its ends to form a plurality of individual strands 4 which will have a substantially square cross section. The number of slits formed in the strip 2 may vary although good results have been obtained by spacing the slits from each other by a distance equal to the thickness of the strip 2 so that each strand will have a substantially square cross section. Slitting may be carried out in any desired manner, for example, by suitable rolls or by a specially designed slitting die. When the slitting operation is carried out with rolls, adjacent strands will be offset from each other as shown in FIG. 7, an arrangement which facilitates subsequent forming operations as described below. Roll slitting is the preferred method of cutting the slits in'the blank for the reason that cables of any desired length and of varying thickness as can be made with one set of rolls.

The slits do not extend to the ends of the cable, but terminate a short distance from the ends to provide a transition zone 6 at each end of the cable, these transition zones being undeformed flat sections of the original strip 2. The ends 8 of the cable may be stamped to form a tongue and holes punched as shown to define conventional ring-tongue terminals.

The transition sections 6 adjacent to the ends of the cable are then curled or bent upwardly and inwardly towards each other as shown at 6' in FIG. 3. After this operation has been carried out, the strands will extend somewhat helically from one transition section 6 to the other and form a cylinder. Thereafter, the ends of the cable are simply twisted. in opposite directions torsionally until the strands are all packed to the desired degree and extend helically along the length of the cable from the one transition section to the other. It will be found that after this twisting operation has been carried out, the cable is relatively flexible in all directions so that the terminal portions 8 on the ends of the cable can be oriented in any desired position relative to each other.

The cable can then be insulated in any desired manner, for example, by the application of shrinkable tubing thereto or by the application of preformed tubing secured to the cable with a suitable adhesive. One preferred form of insulation for automotive battery ca bles is applied by dipping the cable (after masking the terminal portions 8) in a suitable plastisol such as polyvinyl chloride and heating the cable after dipping to cure the plastisol. It may, under some circumstances, be desirable to repeat the dipping and heat curing process several times in order to achieve the desired insulation thickness. In any event, the plastisol will completely cover the cable, excepting for the masked portions thereof, and will penetrate and fill the voids 12 at the ends of the cable formed by the transition sections 6 as shown in .FIG. 6. The plastisol will further penetrate between the strands at the ends of the cable as indicated in FIG. 6 and, to some extent, will penetrate the spaces between the outer strands along the. entire length of the cable as shown in FIG. 5. The finished insulating jacket is thus extremely tenacious and interlocked with the strands so that it will not separate therefrom. The sealed ends of the cables, indicated at 12 in FIG. 6, will prevent the penetration'of the ends of the strands by any corrosive fluids should the cable be used in a corrosive environment.

As alternatives to the plastisol dipping process described above, the insulating coating can be applied by injection molding or vulcanizing, processes which will also result in penetration of insulating material into the strands. ,The insulating material can be any moldable and flexible, dielectric which is suitable forthe conditions of service under'which the cable will be used.

" FIG. 8 shows an alternative embodiment in which the insulating material forms a continuous matrix in'which the cablestrands are embedded. This structure can be achieved 'by limiting the number of twists imparted to the cable so that the strands are not packed tightly together at any location along the length of the cable. This structure is advantageous where the cable will be subjected to severe vibration conditions in that the individual strands will be prevented from responding to external vibrations and adverse metallurgical fatigue effects will be avoided. The structure of FIG. 8 is also advantageous in that repititious flexure of the cable will If desired, the exposed end terminals 8 of the finished cable of FIG. 4 can be suitably plated with any metal which is compatible with the metal of the terminal to which the cable is being attached. It has been found,

, however, that unplated aluminum will yield satisfactory results over a long period of time and that no more servicing of the cable terminals is required than is required withpreviously known types of terminals on battery cables.

Under some circumstances, a flat cable rather than a round cable may be desired and this structure can be achieved by simply applying the insulating material to the formed cable of FIG. 2' rather than twisting and forming the cable as shown in FIG. 3. A flat cable as shown in FIG. 9 is extremely flexible in -directions extending normally of its original plane but it is not flexible in its own plane. Under some circumstances, the flexibility of the cable inits own plane is not needed although the reduced thickness obtained with a flat cable is desirable.

FIG. 10 shows an alternative embodiment comprising a cable 14 having a conventional ring tongue terminal 8 on its right hand end and having a terminal formed to conform to a battery post 26 on its left hand end. The right hand end of the cable is formed and twisted as described above. The left hand end portion is folded as shown at 16 and the parallel imperforate folds are riveted together as shown at 18. The end portions are formed to provide a conical receptacle 20 composed of two sections, one of which extends from each of the folds 16. These sections have integral cars 22 so that a fastener 24 can be employed to clamp the conical receptacle against the conical surface of the terminal 26 of battery 28. The cable -14 can be provided with insulation in the manner previously described.

Cables in accordance with the invention can be manufactured from any suitable conductor metal including copper. In all cases, economies will be realized with regard to the elimination of the costs of the terminals although in the case of extremely long cables, I

these costs will be less significant than for relatively short cables such as those used with automotive batteries. As noted previously, the invention has particular economic advantages where aluminum cables are used becauseof the extraordinary costs of the terminating aluminum conductors which would otherwise offset the economies realized by using. aluminum cable rather than copper cable. 7

Changes in construction will occur to those skilled in the art and various apparently different modifications and embodiments may be made without departing from the scope of the invention. The matter set forth in the foregoing description and accompanying drawings if offered .by way of illustration only.

What is claimed is:

1. An electrical cable comprising:

a continuous strip of conductive sheet metal, v

a plurality of parallel slits extending axially along said cable intermediate the ends thereof, said slits defining a plurality of cable strands, each of which has a rectangular cross section,

a transition section of imperforate sheet metal adjacent to each end of said strip,

terminal means integral with, and extending from,

said transition sections, and

an insulating coating on saidcable in coveringinsulating relationship to at least said strands.

2. A cable as set forth in claim 1 wherein said cable is substantially flat, said strands permitting flexure of said cable normally of its own plane.

3.'A cable as set forth in claim I wherein said transition sections have lateral side portions which are bent inwardly and towards each other, said strands extending helically between said transition sections.

4. A cable as set forth in claim 3 wherein said cable is torsionally twisted and said strands are closely packed within said insulating coating. i

5. A cable as set forth in claim 3 wherein said insulating material comprises a continuous mating extending between said terminal means, in surrounding relationship to each of said strands, and filling the space enclosed by said formed transition sections.

6. A cable as set forth in claim 1 wherein one of said terminal means comprises a clamp adapted to be connected to a battery terminal.

6 7. A cable as set forth in claim 1 in which the transia terminal section integral with and extending from tion section at one end of said cable is folded in the each of said transition sections. axial direction of said cable to form a pair of plate-like 9, A th d of manufacturing an electrical cable Sections, Said Sections being formed outwardly to from a strip of conductive sheet metal comprising the define opposed contact surfaces, and means on said 5 Steps f;

one end for securing said sections to each other and clamping said surface against a battery terminal.

8. A sheet metal electrical cable comprising:

a plurality of individual strands, said strands each having a rectangular cross section and extending 10 generally helically along the length of said cable so that said cable has a generally circular cross section,

a transition section at each end of said cable, each of said transitions comprising a sheet metal section having a developed width which is substantially equal to the sum of the widths of all of said inslitting said sheet along a plurality of parallel shear lines extending intermediate the ends of said strip to define a plurality of parallel strands,

blanking end portions of said strip to provide integral terminal means spaced from the ends of said strands,

bending side portions of said strip which lie between said terminal means and the ends of said strands inwardly towards each other to form cylindrical cross sections adjacent to each end of said cable,

twisting said strip torsionally along the axis thereof to dividual strands, each of said transition sections impart a helkfal configlnation to Said Strands being curled so that the lateral edges thereof are flowing insulating material over the surface of sa d adjacent to each strands and into the enclosures defined by said said individual strands being integral with, and exbent Pomons' tending from said transition section, and 

1. An electrical cable comprising: a continuous strip of conductive sheet metal, a plurality of parallel slits extending axially along said cable intermediate the ends thereof, said slits defining a plurality of cable strands, each of which has a rectangular cross section, a transition section of imperforate sheet metal adjacent to each end of said strip, terminal means integral with, and extending from, said transition sections, and an insulating coating on said cable in covering insulating relationship to at least said strands.
 2. A cable as set forth in claim 1 wherein said cable is substantially flat, said strands permitting flexure of said cable normally of its own plane.
 3. A cable as set forth in claim 1 wherein said transition sections have lateral side portions which are bent inwardly and towards each other, said strands extending helically between said transition sections.
 4. A cable as set forth in claim 3 wherein said cable is torsionally twisted and said strands are closely packed within said insulating coating.
 5. A cable as set forth in claim 3 wherein said insulating material comprises a continuous mating extending between said terminal means, in surrounding relationship to each of said strands, and filling the space enclosed by said formed transition sections.
 6. A cable as set forth in claim 1 wherein one of said terminal means comprises a clamp adapted to be connected to a battery terminal.
 7. A cable as set forth in claim 1 in which the transition section at one end of said cable is folded in the axial direction of said cable to form a pair of plate-like sections, said sections being formed outwardly to define opposed contact surfaces, and means on said one end for securing said sections to each other and clamping said surface against a battery terminal.
 8. A sheet metal electrical cable comprising: a plurality of individual strands, said strands each having a rectangular cross section and extending generally helically along the length of said cable so that said cable has a generally circular cross section, a transition section at each end of said cable, each of said transitions comprising a sheet metal section having a developed width which is substantially equal to the suM of the widths of all of said individual strands, each of said transition sections being curled so that the lateral edges thereof are adjacent to each other, said individual strands being integral with, and extending from said transition section, and a terminal section integral with and extending from each of said transition sections.
 9. A method of manufacturing an electrical cable from a strip of conductive sheet metal comprising the steps of: slitting said sheet along a plurality of parallel shear lines extending intermediate the ends of said strip to define a plurality of parallel strands, blanking end portions of said strip to provide integral terminal means spaced from the ends of said strands, bending side portions of said strip which lie between said terminal means and the ends of said strands inwardly towards each other to form cylindrical cross sections adjacent to each end of said cable, twisting said strip torsionally along the axis thereof to impart a helical configuration to said strands, and flowing insulating material over the surface of said strands and into the enclosures defined by said bent portions. 